Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Ultrasonic distance measurement systems are widely used in industry and other areas such as automobiles, construction industry, surveying applications, and comparable ones. Such systems typically include electronic components to excite the piezoelectric transducer and to sense reflected signal. High-end systems may employ complex and expensive integrated circuits to perform the tasks, while less expensive solutions that are built on general purpose discrete components may not provide satisfactory performance regarding performance, price, and/or size.
Ultrasonic Sound Navigation and Ranging (SONAR) systems may typically include a central controller module and one or more sensors. The central module usually incorporates a micro-controller that excites and polls the sensors, receives and analyzes SONAR echoes, and produces visual or audio cues that indicate the presence or absence of objects, and in some cases the distance to the objects. In a typical application, each sensor may be housed in an enclosure that incorporates a ceramic transducer and electronic components to excite the transducer (to produce a “ping”) and to sense the response of the same transducer to echoes.
A common and relatively inexpensive approach for SONAR applications is to build sensors from general-purpose amplifiers, discrete transistors, and other discrete components. In such an approach, the sensor amplifies and filters the transducer response, but delegates to the central controller the task of recognizing and interpreting echoes in the resulting analog signal. One challenge facing many ultrasonic SONAR systems is significant variability in transducer sensitivity resulting from manufacturing variations. If not accounted for, such variability may cause false alerts or detection failures. To compensate for variations in transducer sensitivity, sensors typically provide a means of adjusting the gain of the receiver amplifier. In simple sensors, for example, gain adjustment may be achieved by manual tuning of potentiometers.